Position determination procedures include timing-based procedures in which timing information for signals transmitted from various wireless devices/nodes are received, measured, and used to derive location information. For example, in observed-time-difference of-arrival (OTDOA) based positioning, a mobile station may measure time differences in received signals from a plurality of network nodes (such as base stations). Because positions of the base stations can be known, the observed time differences may be used to calculate the location of the mobile device.
To further help location determination, Positioning Reference Signals (PRS) may be provided in order to improve OTDOA positioning performance (and/or performance of other position determination procedures). The measured time difference of arrival of the PRS from a reference cell (or other reference point such as a positioning beacon) and one or more neighboring cells is known as the Reference Signal Time Difference (RSTD). Using the RSTD measurements, the absolute or relative transmission timing of each cell, and based on the known position(s) of nodes (e.g. physical transmitting antennas for the reference and neighboring cells), the position of a receiving mobile device may be derived.